(A) Field of the Invention
The present invention relates to an optical frequency mixer and method for the same, and more particularly, to an optical frequency mixer using a resonant cavity having a nonlinear crystal to generate a wavelength shifting through a nonlinear frequency mixing process and the method for the same.
(B) Description of the Related Art
Nonlinear crystal, including periodically poled domains on a ferroelectric single crystal such as lithium niobate, may be widely used in technical fields such as optical storage, optical measurement and optical communication. Particularly, nonlinear optical crystals are also proposed to be used for optical frequency mixing to generate a laser beam having a certain wavelength from at least one source beam through a nonlinear frequency mixing process.
U.S. Pat. No. 6,762,876 discloses an optical converter with a designated output wavelength. The optical converter includes an optical sum frequency generator (SFG) and an optical difference frequency generator (DFG). The SFG receives part of both an input beam carrying information and a continuous-wave (CW) optical pump beam, while the DFG receives part of the input beam as well as the output of the SFG. The output of the DFG represents the signal of the input beam modulated on a beam having the frequency of the pump beam.
U.S. Pat. No. 6,697,391 discloses an optical fourth-harmonic generation system including a V-shaped resonant cavity configured to support an electromagnetic radiation of a fundamental frequency and a fourth-harmonic generator (FHG) disposed within the resonant cavity to produce an electromagnetic radiation of a fourth-harmonic frequency by an interaction with the electromagnetic radiation of the fundamental frequency. The fundamental radiation is characterized by a p-polarization that is complementary to an s-polarization that characterizes the fourth-harmonic radiation. The fourth-harmonic generator has an output facet oriented substantially at a Brewster's angle with respect to the fundamental radiation to separate the fundamental radiation from the fourth-harmonic radiation as they emerge from the output facet.
U.S. Pat. No. 6,726,763 discloses a nonlinear crystal having an increased spectral acceptance. The nonlinear crystal includes a plurality of domains arranged serially across the nonlinear crystal, and has alternating polarity. The poling periods of the domains are varied across the nonlinear crystal so as to provide nonuniform chirping of phase matching of focused optical signals propagated through the nonlinear crystal.